Microcalorimetric studies on the physical stability of poly-ethylene glycol-grafted liposome

Der Zen Liu, Yi Ling Hsieh, Sheng Yen Chang, Wen Yih Chen

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Liposomes were prepared from mixtures of egg-PC, cholesterols and distearoyl-phosphatidyl-ethanolamine covalently attached poly-ethylene glycol (PEG) with a molecular of weight 2000 (DSPE-PEG2000). In this work examines how PEG2000-grafted lipids affect the surface properties of the egg phosphatidylcholine (egg-PC) liposomal bilayer membrane through zeta potential and interaction potential measurements using microcalorimetry. Experimental results demonstrate that the absolute value of the zeta potential of PEG2000-grafted PC liposomes decreased from -19 to -8 mV when increasing DSPE-PEG2000 from 0 to 7 mol fraction, and the repulsive interaction potential of PEG2000-grafted PC liposomes decreased compared with those liposomes without PEG-grafting. However, the phenomenon of fusion between the liposomes incorporated with PEG-grafted PC was reduced. In brief, this result of fusion is contrary to the expectation of the interaction potential measurement; therefore, we believe that the steric hindrance of the grafted PEG2000 molecules on the liposomal surface contribute to a major imposition on the approach between liposomal surface and the formation of inverted micelles which are suggested as the necessary steps of liposome fusion.

Original languageEnglish
Pages (from-to)227-234
Number of pages8
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Issue number2-3
Publication statusPublished - Jan 23 2003


  • Interaction potential
  • Physical stability
  • Poly-ethylene glycol-liposome
  • Zeta potential

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry


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